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Bifurcation of thermocapillary convection in a shallow annular pool of silicon melt

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Acta Mechanica Sinica 2007年第1期23卷 43-48页

作者： yourong li Lan Peng Shuangying Wu Nobuyuki Imaishi College of Power Engineering Chongqing University Chongqing 400044 China Institute for Materials Chemistry and Engineering Kyushu University Fukuoka 816-8580 Japan

In order to understand the nature of surface patterns on silicon melts in industrial Czochralski furnaces, we conducted a series of unsteady threedimensional numerical simulations of thermocapillary convections in thin silicon melt pools in an annular container. The pool is heated from the outer cylindrical wall and cooled at the inner wall. Bottom and top surfaces are adiabatic. The results show that the flow is steady and axisymmetric at small temperature difference in the radial direction. When the temperature difference exceeds a certain threshold value, hydrothermal waves appear and bifurcation occurs. In this case, the flow is unsteady and there are two possible groups of hydrothermal waves with different number of waves, which are characterized by spoke patterns traveling in the clockwise and counter-clockwise directions. Details of the flow and temperature disturbances are discussed and number of waves and traveling velocity of the hydro- thermal wave are determined.

关键词： Computer simulation Thermocapillary convection Semiconducting silicon Bifurcation

Two-dimensional numerical simulation of thermocapillary convection in detached solidification

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Science China(Technological Sciences) 2012年第2期55卷 527-536页

作者： PENG Lan FAN JuYan li yourong MENG HaiYong Key Laboratory of Low-grade Energy Utilization Technologies and Systems of Ministry of Education(Chongqing University) Chongqing 400044China

Numerical simulations of flow in the melt(CdZnTe) with different conditions are conducted using the finite-difference *** the top surface of the melt is solid wall under microgravity condition,the thermocapillary convection is caused in the melt by the surface tension gradient on the free *** the Marangoni number is small,the flow is steady thermocapillary *** the Marangoni number exceeds the critical value,the steady flow transits into unstable thermocapillary *** the top surface of the melt is free surface under microgravity,two roll cells are observed in the melt,which are driven by both the surface tension gradients on the upper and lower free *** the top surface of the melt is free surface under gravity condition,the effect of the buoyancy on the flow is little as the Marangoni number is *** the Marangoni number increasing,the effect of the buoyancy increases,which makes the upper roll cell weaken and the lower roll cell strengthen.

关键词： detached solidification thermocapillary convection buoyancy CdZnTe numerical simulation

Steady thermal-solutal capillary convection in a shallow annular pool with the radial temperature and concentration gradients

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Science China(Technological Sciences) 2012年第8期55卷 2176-2183页

作者： li yourong GONG ZhenXing WU ChunMei WU ShuangYing Key Laboratory of Low-grade Energy Utilization Technologies and Systems of Ministry of Education College of Power EngineeringChongqing UniversityChongqing 400044China

Using asymptotical analysis,we investigate the characteristics of the coupled thermal and solutal capillary convection with the radial temperature and solute concentration gradients in a shallow annular pool with the free *** pool is heated from the outer cylinder with high solutal concentration and cooled at the inner cylinder with low solutal *** asymptotic solution is obtained in the core region in the limit as the aspect ratio,which is defined as the ratio of the depth to the width of the pool,goes to *** comparison with the previous work certifies that the asymptotic solution is right and *** influences of the solutal capillary force,the buoyant force,the Soret effect and the geometric parameters on the fluid flow are analyzed.

关键词： coupled thermal and solutal capillary convection asymptotic solution buoyancy Soret effect

Instability of forced flow in a rotating cylindrical pool with a differentially rotating disk on the free surface

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Science China(Technological Sciences) 2010年第9期53卷 2477-2488页

作者： WU ChunMei & li yourong College of Power Engineering,Chongqing University,Chongqing 400044,China 1. College of Power Engineering Chongqing University Chongqing 400044 China

The instability of forced flow in a rotating cylindrical pool with a differentially rotating disk on the free surface is investigated through a series of unsteady three-dimensional numerical *** results show that the basic flow state of this system is axisymmetric and steady,but has rich structures at the meridian ***,when the rotation Reynolds number exceeds a critical value,the flow will undergo a transition to three-dimensional oscillatory flow,characterized by the velocity fluctuation waves traveling in the azimuthal *** main characteristics of the flow patterns are presented,including the propagating direction,velocity,amplitude and wave number,which depend on the rotation rates and directions of the disk and the cylindrical pool,and the critical conditions for the onset of oscillatory flow are also *** the case of disk-only rotation,the centrifugal instability is responsible for the flow transition,and when the disk isoand counter-rotates with the cylindrical pool,the mechanisms for the transition are elliptic and of circular shear instabilities,respectively.

关键词： rotation flow transition flow instability

Asymptotic solution of thermocapillary convection in two immiscible liquid layers in a shallow annular cavity

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Science China(Technological Sciences) 2010年第6期53卷 1655-1665页

作者： li yourong,WANG ShuangCheng,WU ShuangYing & SHI WanYuan College of Power Engineering,Chongqing University,Chongqing 400044,China 1. College of Power Engineering Chongqing University Chongqing 400044 China

The steady laminar two-dimensional thermocapillary convection of two superposed horizontal liquid layers in a shallow annular cavity was investigated using asymptotical *** liquids were supposed to be immiscible with a nondeformable *** cavity was heated from the outer cylindrical wall and cooled at the inner *** and top surfaces were rigid and *** solutions were obtained in the core region in the limit as the aspect ratio,which was defined as the ratio of the lower layer thickness to the gap width,and trended to *** numerical experiments were also carried out to compare with the asymptotic solution of the steady two-dimensional thermocapillary *** is found that the expressions of velocity and temperature fields in the core region are valid in the limit of the small aspect ratio.

关键词： asymptotic solution thermocapillary flow two-layer system shallow annular cavity

A comparative study on thermo-economic performance between subcritical and transcritical Organic Rankine Cycles under different heat source temperatures

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Chinese Science Bulletin 2014年第28期59卷 4379-4387页

作者： Shuangying Wu Chun li Lan Xiao Chao liu yourong li Key Laboratory of Low-grade Energy Utilization Technologies and Systems Ministry of Education Chongqing University College of Power Engineering Chongqing University

In this paper, the net power output, exergy efficiency and levelized energy cost of system were selected as performance indicators for assessing Organic Rankine Cycle(ORC). Firstly, the turbine inlet temperature and pressure meeting the requirement of pinch point temperature difference of evaporator in transcritical ORC(trans-ORC) were determined based on performance optimization. Subsequently, the thermo-economic performance of a subcritical ORC(sub-ORC) using R601 as working fluid and a trans-ORC using R134 a as working fluid were compared under different heat source temperatures and a fixed outlet temperature of flue gas. Results show that for trans-ORC, when the pinch point temperature difference of evaporator lies between the inlet and outlet of evaporator, a lower inlet pressure of turbine is favorable; when the pinch point temperature difference of evaporator is located at the outlet of evaporator, there exists an optimal inlet pressure of turbine. Either for sub-ORC or trans-ORC, the net power output increases and levelized energy cost decreases with the increase in heat source temperature. For sub-ORC,exergy efficiency of system increases monotonously with heat source temperature, while for trans-ORC, exergy efficiency of system grows up firstly and then reduces(or keeps constant) with the increasing of heat source temperature. Moreover, for net power output and exergy efficiency of system, there exist a range of heat source temperatures making trans-ORC better than sub-ORC, and the heat source temperature region extends with the increase in pinch point temperature difference of evaporator. For levelized energy cost of system, the sub-ORC is always superior to trans-ORC.

关键词：热源温度经济性能朗肯循环跨临界亚临界功率输出能源成本出口温度

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A Cold Model Experimental Study on the Flow Characteristics of Bed Material in a Fluidized Bed Bottom Ash Cooler in a CFB Boiler

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Journal of Thermal Science 2000年第4期9卷 381-384页

作者： Lu Xiaofeng,li yourong (Institute of Thermal Energy Engineering, Chongqing University, Chongqing, 400044, China) Institute of Thermal Energy Engineering Chongqing University Chongqing China

A cold model experimental study on the flowing characteristics of bed material between a fluidized bed ash cooler and a furnace of CFB boiler were discussed in this paper. The research results showed that flowing status of the bed material in a bubbling bed, which was run with a circulating fluidized bed together in parallel operation, was influenced by the pressure difference between the CFB and the bubbling bed, the switch status of unlocking air, and the structure of the exit of the bubbling bed. There was a circulating flow of bed material between CFB and bubbling bed.

关键词： fluidized bed CFB bottom ash cooler.

低纬高原甘蔗中后期灾害性真菌病害综合防控技术系统构建

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甘蔗糖业 2024年第2期53卷 33-39页

作者：王晓燕徐宏李有荣赵曌李婕孙石凤王雪梅单红丽张荣跃黄应昆云南省农业科学院甘蔗研究所/云南省甘蔗遗传改良重点实验室云南开远661699 云南紫辰农业发展有限公司云南大理672100 新平县经济作物工作站云南玉溪653400

针对低纬高原甘蔗中后期灾害性真菌病害防控难题,在明确甘蔗中后期灾害性真菌病害种类及病原种类、地理分布、危害损失和灾害特性的基础上,提出利用“早期诊断预警、抗病品种、温水脱毒种苗、农艺调控、无人机飞防、生物制剂及复合高效... 详细信息

针对低纬高原甘蔗中后期灾害性真菌病害防控难题,在明确甘蔗中后期灾害性真菌病害种类及病原种类、地理分布、危害损失和灾害特性的基础上,提出利用“早期诊断预警、抗病品种、温水脱毒种苗、农艺调控、无人机飞防、生物制剂及复合高效配方药剂”等构建低纬高原甘蔗中后期灾害性真菌病害综合防控技术系统。同时,从病害流行动态精准监测技术、抗病基因挖掘与利用技术、抗病精准评价技术、生防制剂和复合高效药剂配方及施药技术和飞防施药技术等方面系统剖析了实现甘蔗中后期灾害性真菌病害综合防控系统构建的关键技术方法。2021~2022年该技术在低纬高原云南8个甘蔗主产州市累计推广应用32.3万hm^(2)(无人机飞防6.7万hm^(2)),共挽回甘蔗损失388万t,增加蔗糖49.7万t,新增销售额42.09亿元,新增利润13.24亿元,增税1.99亿元,经济、社会和生态效益显著,为低纬高原蔗糖业可持续高质量发展、减损增效提供了技术支撑,为边疆民族经济发展和农民增收及乡村振兴做出了重大贡献。

关键词：甘蔗中后期真菌病害低纬高原综合防控

基于边缘计算与农业物联网的温室监测系统设计与实现

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南方农业 2024年第17期18卷 245-251页

作者：普金安白华飞孙石凤李有荣徐国富张翠英王婷杨琳琳新平彝族傣族自治县经济作物工作站云南玉溪653400 新平彝族傣族自治县种子管理站云南玉溪653400 新平彝族傣族自治县者竜乡农业农村综合服务中心云南玉溪653400 云南农业大学机电工程学院云南昆明650201

针对温室作业环境分散复杂\监控系统不易进行大规模部署等问题,设计一种基于边缘计算与农业物联网的温室环境监测系统(GEMS)。1)在建立边缘计算与农业物联网相互融合的系统体系构架基础上,对温室环境监测系统的上位机、下位机进行需求... 详细信息

针对温室作业环境分散复杂\监控系统不易进行大规模部署等问题,设计一种基于边缘计算与农业物联网的温室环境监测系统(GEMS)。1)在建立边缘计算与农业物联网相互融合的系统体系构架基础上,对温室环境监测系统的上位机、下位机进行需求建模。2)根据需求模型对上、下位机进行详细设计。上位机包括后台管理、实时监测、历史数据查询和数据分析等模块。下位机系统是由Arduino与多种环境传感器组成的数据采集模块、采用LoRa技术实现数据无线传输的通信模块、能对采集数据进行预处理的边缘计算模块和实现各节点间相互通讯的网关模块组成。3)基于B/S架构,采用Django Web框架、WebSocket协议、Ajax技术实现GEMS原型系统。

关键词：农业物联网边缘计算温室环境监测系统 Django Web框架嵌入式系统

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